Remove some incorrect else-if logic in time plugin

It looks like there was some incorrect else-if logic introduced in the time plugin @ f8064ca7ea4f3ff20516c0376d8c24841fdc7ec2

Before that commit, our chart looks this: http://d.pr/i/2YXq

Note the crosshair is just before the Feb month tick and the legend says Jan 31 - good.

After that commit, our chart looks like this: http://d.pr/i/lewG

Besides the fact that a new tick was added, the crosshair is again just before the Feb month tick but the legend says Feb 15 - so that's not right.

I corrected the offending change here and now it works again.

This may be related to #1017